238 lines
6.8 KiB
C
238 lines
6.8 KiB
C
#include <assert.h>
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#include <mmu.h>
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#include <x86.h>
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#include <kern/protect.h>
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#include <kern/stdio.h>
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#include <kern/trap.h>
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struct Pseudodesc gdt_ptr, idt_ptr;
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DESCRIPTOR gdt[GDT_SIZE];
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DESCRIPTOR ldt[LDT_SIZE];
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GATE idt[IDT_SIZE];
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TSS tss;
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/*
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* 当发生不可挽回的错误时就打印错误信息并使CPU核休眠
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*/
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void
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_panic(const char *file, int line, const char *fmt,...)
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{
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va_list ap;
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// 确保CPU核不受外界中断的影响
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asm volatile("cli");
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asm volatile("cld");
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va_start(ap, fmt);
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kprintf("\x1b[0m\x1b[91mkernel panic at %s:%d: ", file, line);
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vkprintf(fmt, ap);
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kprintf("\n\x1b[0m");
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va_end(ap);
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// 休眠CPU核，直接罢工
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while(1)
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asm volatile("hlt");
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}
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/*
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* 很像panic，但是不会休眠CPU核，就是正常打印信息
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*/
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void
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_warn(const char *file, int line, const char *fmt,...)
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{
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va_list ap;
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va_start(ap, fmt);
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kprintf("\x1b[0m\x1b[93mkernel warning at %s:%d: ", file, line);
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vkprintf(fmt, ap);
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kprintf("\n\x1b[0m");
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va_end(ap);
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}
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/*
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* 再创建一遍gdt表，与loader中的gdt表不同的是
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* 新增了tss和ldt的两个的全局描述符
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*/
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static void
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init_gdt(void)
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{
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init_segment(&gdt[0], 0, 0, 0);
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// 代码段(cs)
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init_segment(&gdt[1], 0, 0xfffff, DA_CR | DA_32 | DA_LIMIT_4K);
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// 数据段(ds,es,fs,ss)
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init_segment(&gdt[2], 0, 0xfffff, DA_DRW | DA_32 | DA_LIMIT_4K);
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// 显存段(gs)
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init_segment(&gdt[3], K_PHY2LIN(0xb8000), 0x8, DA_DRW | DA_DPL3 |
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DA_32 | DA_LIMIT_4K);
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tss.ss0 = SELECTOR_FLAT_RW;
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tss.iobase = sizeof(tss); /* 没有I/O许可位图 */
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// tss段
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init_segment(&gdt[4], (u32)&tss, sizeof(tss) - 1, DA_386TSS);
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// ldt段
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init_segment(&gdt[5], (u32)ldt, sizeof(ldt) - 1, DA_LDT);
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gdt_ptr.pd_base = (u32)gdt;
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gdt_ptr.pd_lim = sizeof(gdt) - 1;
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}
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/*
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* 创建ldt表，ldt表用于用户态，用户进程的段寄存器不能存放内核权限的gdt
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* ，而是使用用户权限的ldt
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*/
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static void
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init_ldt(void)
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{
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init_segment(&ldt[0], 0, 0, 0);
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// 代码段(cs)
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init_segment(&ldt[1], 0, 0xfffff,
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DA_CR | DA_32 | DA_LIMIT_4K | DA_DPL3);
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// 数据段(ds,es,fs,ss)
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init_segment(&ldt[2], 0, 0xfffff,
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DA_DRW | DA_32 | DA_LIMIT_4K | DA_DPL3);
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// 用户态的gs继承自gdt的显存段
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}
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/*
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* 创建idt表，看起来挺吓人的，实际上全是按照手册抄的。
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*/
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static void
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init_idt(void)
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{
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// 异常处理
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init_gate(idt + INT_VECTOR_DIVIDE, DA_386IGate,
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divide_error, PRIVILEGE_KRNL);
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init_gate(idt + INT_VECTOR_DEBUG, DA_386IGate,
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single_step_exception, PRIVILEGE_KRNL);
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init_gate(idt + INT_VECTOR_NMI, DA_386IGate,
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nmi, PRIVILEGE_KRNL);
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init_gate(idt + INT_VECTOR_BREAKPOINT, DA_386IGate,
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breakpoint_exception, PRIVILEGE_USER);
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init_gate(idt + INT_VECTOR_OVERFLOW, DA_386IGate,
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overflow, PRIVILEGE_USER);
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init_gate(idt + INT_VECTOR_BOUNDS, DA_386IGate,
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bounds_check, PRIVILEGE_KRNL);
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init_gate(idt + INT_VECTOR_INVAL_OP, DA_386IGate,
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inval_opcode, PRIVILEGE_KRNL);
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init_gate(idt + INT_VECTOR_COPROC_NOT, DA_386IGate,
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copr_not_available, PRIVILEGE_KRNL);
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init_gate(idt + INT_VECTOR_DOUBLE_FAULT,DA_386IGate,
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double_fault, PRIVILEGE_KRNL);
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init_gate(idt + INT_VECTOR_COPROC_SEG, DA_386IGate,
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copr_seg_overrun, PRIVILEGE_KRNL);
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init_gate(idt + INT_VECTOR_INVAL_TSS, DA_386IGate,
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inval_tss, PRIVILEGE_KRNL);
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init_gate(idt + INT_VECTOR_SEG_NOT, DA_386IGate,
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segment_not_present, PRIVILEGE_KRNL);
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init_gate(idt + INT_VECTOR_STACK_FAULT, DA_386IGate,
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stack_exception, PRIVILEGE_KRNL);
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init_gate(idt + INT_VECTOR_PROTECTION, DA_386IGate,
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general_protection, PRIVILEGE_KRNL);
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init_gate(idt + INT_VECTOR_PAGE_FAULT, DA_386IGate,
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page_fault, PRIVILEGE_KRNL);
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init_gate(idt + INT_VECTOR_COPROC_ERR, DA_386IGate,
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copr_error, PRIVILEGE_KRNL);
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// 外设中断
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init_gate(idt + INT_VECTOR_IRQ0 + 0, DA_386IGate,
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hwint00, PRIVILEGE_KRNL);
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init_gate(idt + INT_VECTOR_IRQ0 + 1, DA_386IGate,
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hwint01, PRIVILEGE_KRNL);
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init_gate(idt + INT_VECTOR_IRQ0 + 2, DA_386IGate,
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hwint02, PRIVILEGE_KRNL);
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init_gate(idt + INT_VECTOR_IRQ0 + 3, DA_386IGate,
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hwint03, PRIVILEGE_KRNL);
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init_gate(idt + INT_VECTOR_IRQ0 + 4, DA_386IGate,
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hwint04, PRIVILEGE_KRNL);
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init_gate(idt + INT_VECTOR_IRQ0 + 5, DA_386IGate,
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hwint05, PRIVILEGE_KRNL);
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init_gate(idt + INT_VECTOR_IRQ0 + 6, DA_386IGate,
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hwint06, PRIVILEGE_KRNL);
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init_gate(idt + INT_VECTOR_IRQ0 + 7, DA_386IGate,
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hwint07, PRIVILEGE_KRNL);
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init_gate(idt + INT_VECTOR_IRQ8 + 0, DA_386IGate,
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hwint08, PRIVILEGE_KRNL);
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init_gate(idt + INT_VECTOR_IRQ8 + 1, DA_386IGate,
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hwint09, PRIVILEGE_KRNL);
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init_gate(idt + INT_VECTOR_IRQ8 + 2, DA_386IGate,
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hwint10, PRIVILEGE_KRNL);
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init_gate(idt + INT_VECTOR_IRQ8 + 3, DA_386IGate,
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hwint11, PRIVILEGE_KRNL);
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init_gate(idt + INT_VECTOR_IRQ8 + 4, DA_386IGate,
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hwint12, PRIVILEGE_KRNL);
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init_gate(idt + INT_VECTOR_IRQ8 + 5, DA_386IGate,
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hwint13, PRIVILEGE_KRNL);
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init_gate(idt + INT_VECTOR_IRQ8 + 6, DA_386IGate,
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hwint14, PRIVILEGE_KRNL);
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init_gate(idt + INT_VECTOR_IRQ8 + 7, DA_386IGate,
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hwint15, PRIVILEGE_KRNL);
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// 系统调用
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init_gate(idt + INT_VECTOR_SYSCALL, DA_386IGate,
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int_syscall, PRIVILEGE_USER);
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idt_ptr.pd_base = (u32)idt;
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idt_ptr.pd_lim = sizeof(idt) - 1;
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}
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/*
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* 初始化8259A，设置外设中断，看起来挺吓人的，实际上全是按照手册抄的。
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*/
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static void
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init_8259A(void)
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{
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outb(INT_M_CTL, 0x11); // Master 8259, ICW1.
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outb(INT_S_CTL, 0x11); // Slave 8259, ICW1.
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// Master 8259, ICW2. 设置 '主8259' 的中断入口地址为 0x20.
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outb(INT_M_CTLMASK, INT_VECTOR_IRQ0);
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// Slave 8259, ICW2. 设置 '从8259' 的中断入口地址为 0x28
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outb(INT_S_CTLMASK, INT_VECTOR_IRQ8);
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// Master 8259, ICW3. IR2 对应 '从8259'.
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outb(INT_M_CTLMASK, 0x4);
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// Slave 8259, ICW3. 对应 '主8259' 的 IR2.
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outb(INT_S_CTLMASK, 0x2);
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outb(INT_M_CTLMASK, 0x1); // Master 8259, ICW4.
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outb(INT_S_CTLMASK, 0x1); // Slave 8259, ICW4.
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outb(INT_M_CTLMASK, 0xFF); // Master 8259, OCW1.
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outb(INT_S_CTLMASK, 0xFF); // Slave 8259, OCW1.
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}
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static void
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init_irq(void)
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{
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// 开启时钟中断
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enable_irq(CLOCK_IRQ);
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// 调整时钟频率至1000Hz
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outb(0x43, 0x34);
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outb(0x40, 1193&0xff);
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outb(0x40, 1193>>8);
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// 开启键盘中断
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enable_irq(KEYBOARD_IRQ);
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}
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/*
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* 内核初始化函数
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*/
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void cstart(void)
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{
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// 清屏并将光标置为开头
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// ANSI转义序列，由\x1b(ascii码27，为Esc)开头的序列
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// 能够控制光标控制终端（linux上也在用这个控制终端）
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// 目前支持的功能在inc/terminal.c中的kprintf函数有写
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// \x1b[2J 清屏
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// \x1b[H 将光标放置到左上角
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kprintf("\x1b[2J\x1b[H");
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kprintf("---loading gdt ");
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init_gdt();
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kprintf("ldt ");
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init_ldt();
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kprintf("8259A ");
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init_8259A();
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kprintf("idt ");
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init_idt();
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kprintf("irq");
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init_irq();
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kprintf("---\n");
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}
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